1. Field of the Invention
The invention generally relates to manipulator systems and more particularly to an improved, highly efficient controller arm for use in achieving real-time control over a remotely related articulated slave arm.
2. Description of the Prior Art
Master-slave systems, sometimes referred to as remote control manipulators, often are employed in a variety of fields. For example, master-slave systems frequently are used for handling radioactive material, toxic material or other dangerous substances located behind a wall designed to protect an operator of the system. For example, see U.S. Pat. No. 3,815,761. Another field in which a master-slave manipulator system is sometimes employed is in underwater exploration. For example, see U.S. Pat. No. 3,414,136, in which such a system is described. Another field in which master-slave manipulator systems are employed is in the exploration of celestial space. For example, see U.S. Pat. No. 3,893,573.
It should therefore be apparent that the prior art is replete with master-slave manipulator systems characterized by a controller subsystem employed in dictating operation of a slave arm. The master-slave manipulator system which embodies the principles of the instant invention is related to a manipulator system disclosed and claimed in U.S. Letters Patent Application, Ser. No. 436,313, filed Jan. 24, 1974, entitled "AN ANTHROPOMORPHIC MASTER/SLAVE MANIPULATOR SYSTEM", now U.S. Pat. No. 4,046,262.
The manipulator system disclosed in the aforementioned U.S. Application includes a controller arm characterized by an articulated tubular sleeve, often referred to as a brace, into which is inserted an arm of an operator. The sleeve includes electrical signal generating devices which sense motion about joints and provide electrical signals indicative of angular displacement of the sleeve segments initiated in response to motion of the operator's arm. The signals thus generated are transmitted to a remotely related slave arm in which these signals are processed and utilized for angularly displacing segments of the slave arm in a manner substantially duplicating the motion of the operator's arm. Thus the sleeve or brace can, for the sake of convenience, be characterized as a kinematic replica of the corresponding slave arm.
While the controller arm disclosed and claimed in the aforementioned Application for Letters Patent functions quite satisfactorily for its intended purpose, it should be apparent that in some instances, usage of the sleeve is impaired by inherent limitations. For example, in order to employ the system disclosed in the aforementioned application, an operator must insert his arm into the sleeve thereof. In order to appreciate the full advantages of the system, it is necessary that the sleeve be custom-fit to the arm of the operator. Therefore, where an operator for whom the sleeve is designed has an unusually small, large, short or long arm, use of the sleeve by another having an arm of different size is impaired. This results in difficulty being encountered in achieving precise control over the slave arm.
Additionally, the size and weight of the sleeve tend to introduce operational problems. This can be more fully appreciated when it is realized that the sleeve must be supported by an operator substantially throughout the performance of a given task, thus the operator is subjected to fatigue. Fatigue becomes particularly significant in time-delayed manipulation tasks where an operator must hold a segment of the sleeve in a stationary interim position during "waiting periods", sometimes for many minutes.
Further, motion biases which tend to occur in various joints at some arm orientations frequently introduce difficulty in achieving desired motion, without application of excessive force. Such tends to result in false or unwanted motion being introduced into the slave arm.
Finally, since the operator's arm is, in effect, captured inside the sleeve and can only be removed by placing the sleeve in predetermined orientation, the operator may not remove his arm without transmitting control signals to the slave arm. This limitation has a propensity to become particularly serious as emergency conditions are encountered during periods of operation of the system.
It is therefore the general purpose of the instant invention to provide an improved articulated controller arm configured and dimensioned to form a miniature kinematic replica of a remotely related slave arm which overcomes the aforementioned difficulties and disadvantages, without diminishing the effectiveness thereof.